JP2006301624A - Multiple illumination source exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for combining outputs of multiple light sources. <P>SOLUTION: The system includes a plurality of light sources, and a rotatable fold mirror oriented at an angle so as to reflect beams from each of the light sources toward the same direction at various times during its rotation. A projection optical system directs the beams toward a substrate. The rotatable fold mirror can be mounted on an air bearing, a magnetic bearing, or a fluid bearing, and can be oriented at about 45 degrees relative to the vertical. An optional fold mirror for folding an optical axis of the system is mounted between the rotatable fold mirror and the projection optical system. The fold mirror can counter-rotate in synchronization with the rotatable fold mirror so as to keep the direction of the beams constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multiple light source that can be used, for example, in a lithography system.

  The manufacture of liquid crystal displays, or flat panel displays (FPDs), includes processes similar to those used in the integrated circuit (IC) industry that produces computer chips. An exposure system is used to project an image of the circuit pattern to expose the photoresist coated substrate. The actual circuit is generated after processing the exposed substrate using standard microlithographic processes. Depending on the design of a particular FPD, this exposure process can be repeated many times on various layers on a single substrate to achieve circuit design. When all the exposure and microlithographic processing steps are completed so that the desired circuit pattern is generated, the substrate is integrated with other components to produce a flat panel display screen.

  Although FPDs have been produced since the late 1980s, current size requirements for FPDs are up to 42 inches diagonal and 54 and 60 inches diagonal are under development. (Note that in the United States, screen dimensions are typically specified using the yard-pound method, and optical design and tool sizing are typically performed in metric.)

  In a lithography system, it is generally a concern to have a light source that outputs sufficient power for exposure, and in lithography systems used for FPD exposure is of particular concern. Modern FPDs have diagonal dimensions up to 60 inches (and beyond in the future) and are very exposed because of the increased exposure area due to the desire to maximize overall FPD manufacturing throughput. An electromagnetic radiation source that outputs a large amount of power is required. For example, the FPD exposure system currently under consideration may require as much as 250 watts of power output to expose a relatively large FPD. A laser is usually used as the light source for this purpose. However, lasers that produce hundreds of watts of power are not available or are very expensive. For example, commercially available lasers are typically in the 10 to 25 watt power range. Furthermore, the cost of laser systems tends to increase exponentially rather than linearly with increasing power output.

  Accordingly, there is a need in the art for an exposure system that is relatively inexpensive and provides a large power output.

  The present invention is directed to a multi-illumination light source apparatus for a lithographic exposure system that substantially avoids one or more of the problems and disadvantages of the related art.

  Thus, a system that combines multiple light sources and the output of multiple light sources including a rotating folding mirror oriented at an angle so as to reflect the beam from each light source toward the same direction at various times during rotation Is provided. A projection optical system guides the beam to the substrate. The light source may be a pulsed laser or a lamp. The rotary folding mirror can be mounted on an air bearing, a magnetic bearing or a fluid bearing (depending on the desired laser power, repetition rate and rotational accuracy) and oriented at about 45 ° relative to the vertical. An optical folding mirror (or prism diffractive element) that folds the optical axis of the system is between the rotary folding mirror and the projection optical system. The folding mirror can be rotated in reverse in synchronization with the rotary folding mirror so as to keep the beam direction constant. The rotary folding mirror can be mounted on the air bearing and is mounted on the air bearing support. The air bearing and the air bearing support have a passage hole through which the beam passes. Alternatively, a rotary folding mirror can be mounted under the air bearing.

  In another embodiment, the method of combining the outputs of multiple light sources includes arranging the multiple light sources on the same plane to guide the beam to the first mirror and to guide the beam in the same direction. Rotating the first mirror on its surface and generating pulses from the light source in synchronization with the rotation of the first mirror. The beam can be guided from the first mirror to the second counter-rotating mirror, and the rotation of the second counter-rotating mirror compensates for the angular displacement of the beam due to the rotation of the first mirror.

  Additional features and advantages of the invention are set forth in the description below. The advantages of the invention are realized and attained by the structure particularly pointed out in the written description.

  It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory and are provided to further illustrate the present invention.

  Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used to designate the same elements in different figures.

  The present invention uses multiple electromagnetic radiation sources to achieve a high power output that is guided to the substrate being exposed. Thus, there is no need to use one very expensive high power electromagnetic radiation source. This is because a plurality of commercially available light sources may be used.

  1 and 2 show an embodiment of the present invention. FIG. 1 shows a top view of a system that combines the outputs of multiple light sources to expose the same area of the substrate, and FIG. 2 shows a side view. As shown in FIGS. 1 and 2, the illumination light source 101 includes light sources 104A, 104B, 104C and 104D mounted on a support base 102. A folding mirror 202 that folds the optical axis of the system is mounted on the rotating air bearing 108 (or magnetic bearing or fluid bearing), and the rotating air bearing 108 is mounted on the (air) bearing support structure 106. The air bearing 108 may be a conventional air bearing as is known in the art. The mirror 202 is oriented and rotated at an angle of 45 ° so that its direction is synchronized with the output beams of the light sources 104A-104C. The output beam is shown as 110A-110D in FIG.

  Note that although only four light sources 104A-104D are shown in FIGS. 1 and 2, the present invention is not limited to a particular number of light sources. For example, a relatively large number (eg, dozens or even hundreds) of such light sources may be used. Further, although the light source 104 is a laser in the illustrated embodiment, preferably a semiconductor laser diode, it is understood that other types of light sources may be used. For example, the light source 104 may be a lamp, a light emitting diode, or other type of laser, such as an Nd: YAG laser, a gas laser, or the like. A typical pulse width obtainable from such a semiconductor laser is about 100 nanoseconds (depending somewhat on how the pulse width is defined).

  FIG. 2 also shows a second optical bending mirror 204 that guides the output of the light source 104 to the projection optical system 206. The projection optical system 206 guides electromagnetic radiation to a substrate (not shown) under exposure. As will be appreciated by those skilled in the art, other optical elements (not shown) such as beam conditioners, illumination optics, etc. may be used to shape and adjust the beam.

  As the mirror 202 rotates, the position of the beam (eg, beam 110A in FIG. 2) on the folding mirror 204 moves. The magnitude of this effect depends on the pulse width and the rotation speed of the mirror 202. When the mirror 202 rotates relatively slowly and the pulse width is relatively short, the positional change of the beam 110A on the mirror 204 is relatively small. However, when the rotation speed of the mirror 202 is increased and the pulse width is increased, the influence becomes more remarkable. This effect may be acceptable for practical applications. If it is not acceptable, it is possible to mount the mirror 204 on the air bearing portion in the same manner as the mirror 202 and to reversely rotate the mirror 202. When the rotation of the mirrors 202 and 204 is synchronized (in the opposite direction), the rotation of the mirror 204 compensates for the angular displacement of the beam due to the rotation of the mirror 202, and the direction of the beam 110A entering the projection optical system 206 remains constant. Become.

  Also, if the pulse profile is approximately symmetric in time, it is preferable to orient the mirror “facing the light source” (and 45 ° downward) that illuminates the mirror at the pulse peak. . If the pulse profile is asymmetric, it is preferable to distribute the energy of the pulse symmetrically in time with respect to the “light source facing” direction of the mirror.

  3 and 4 show an alternative embodiment of the present invention that uses a rotating air bearing with a beam through hole. As shown in FIGS. 3 and 4, the air bearing portion 302 is attached to the air bearing portion support 310. The mirror 202 is attached to the air bearing 302. A beam (eg, beam 110A from light source 104A) reflects downward from mirror 202, similar to the embodiment of FIGS. The beam passes through the hole 306 toward the mirror 204 and then toward the projection optical system 206.

  One advantage of the embodiment of FIGS. 3 and 4 is that it simplifies the problem of alignment of the mirror 202 with respect to the light source 104.

  FIG. 5 illustrates a system 500 according to one embodiment of the invention. The system 500 includes an illumination light source 101 that outputs light to the illumination optical system 504. The illumination optics 504 guides light through the mask or reticle 506 (or from there) through the projection optics 206 to the substrate 508. One application of this system is a lithography system or the like. Another application is a holography system, or a laser welding system, or laser machining, or a similar application, such as a weapon. This is because the present invention is not limited to lithography applications and may be used for other applications that require high power light sources.

  Those skilled in the art will recognize that various changes can be made in form and detail without departing from the spirit and scope of the invention as defined in the claims. Accordingly, the breadth and scope of the present invention is not limited to any of the above-described exemplary embodiments, but is defined only by the claims and their equivalents.

1 shows a top view of one embodiment of the present invention. FIG. 1 shows a side view of one embodiment of the present invention. FIG. 6 shows a top view of an alternative embodiment of the present invention. FIG. 6 shows a side view of an alternative embodiment of the present invention. 1 depicts a lithography system according to an embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Illumination light source 102 Support stand 104 Light source 106 Support structure 108 Air support part 110 Output beam 202 Mirror 204 Mirror 206 Projection optical system 302 Air support part 306 Hole 310 Air support part support body 500 System 504 Illumination optical system 506 Reticle 508 Substrate

Claims (21)

A system that combines the output of multiple light sources,
Multiple light sources;
A rotating folding mirror oriented at an angle to reflect the beam from each light source in the same direction at various times during rotation;
A projection optical system for guiding the beam to the substrate.   The system of claim 1, wherein the plurality of light sources comprises a pulsed laser.   The system of claim 1, wherein the plurality of light sources comprises a lamp.   The system of claim 1, wherein the rotary folding mirror is mounted on one of an air bearing, a fluid bearing or a magnetic bearing.   The system of claim 1, wherein the rotating folding mirror is oriented at approximately 45 ° with respect to the beam incident path.   The system of claim 1, further comprising a folding mirror that folds the optical axis of the system between the rotary folding mirror and the projection optical system.   The system of claim 1, wherein the folding mirror rotates counterclockwise in synchronization with the rotating folding mirror so as to maintain the beam direction constant.   The system according to claim 1, wherein the rotary folding mirror is mounted on the air bearing support, and the air bearing and the air bearing support have a passage hole through which the beam passes.   The system of claim 1, wherein the rotary folding mirror is coupled to the air bearing and mounted under the air bearing.   The system of claim 1, wherein the substrate is a flat panel display.   The system of claim 1, wherein the substrate is a semiconductor wafer. A method of combining the output of multiple light sources,
Arranging a plurality of light sources on the same plane and guiding the beam to the first mirror;
Rotating the first mirror in the plane to guide the beam in the same direction;
Generating pulses from the light source in synchronization with rotation of the first mirror.   13. The method of claim 12, further comprising guiding the beam from the first mirror to a second counter-rotating mirror, wherein rotation of the second counter-rotating mirror compensates for angular displacement of the beam due to rotation of the first mirror. the method of.   The method of claim 12, wherein the plurality of light sources comprises a pulsed laser.   The method of claim 12, wherein the plurality of light sources comprises a lamp.   The method of claim 12, wherein the first mirror is mounted on the air bearing.   The method of claim 12, further comprising orienting the first mirror at about 45 ° with respect to the beam incident path.   The method of claim 12, further comprising exposing the substrate to a beam.   The method of claim 12, wherein the substrate is a flat panel display. A method for exposing a substrate, comprising:
Arranging a plurality of light sources on the same plane and guiding the beam to the first mirror;
Rotating the first mirror in the plane to guide the beam in the same direction;
Generating pulses from the light source in synchronization with the rotation of the first mirror;
Exposing the beam to exposure. A system that combines the output of multiple light sources,
Multiple light sources;
A rotating prism oriented to reflect the beam from each light source in the same direction at various times during rotation;
A projection optical system for guiding the beam to the substrate.

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